Can Propagation of Gas Bubbles Lead to Detached Solidification? Experiments on Freezing of Water

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• 作者：Yazhen Wang ; Liya L. Regel ; and William R. Wilcox
• 刊名：Crystal Growth & Design
• 出版年：2002
• 出版时间：September 2002
• 年：2002
• 卷：2
• 期：5
• 页码：453 - 461
• 全文大小：362K
• 年卷期：v.2,no.5(September 2002)
• ISSN：1528-7505

文摘

A vertical Bridgman-Stockbarger apparatus was used to directionally solidify water upward, in thehope that detached solidification would evolve from gas bubbles forming on the wall. A large contact angle of thewater on the ampoule wall and a high solubility of the dissolved gas caused gas bubbles or tubes to form only at theampoule wall, and not in the interior. Gas tubes were often nearly periodically spaced around the ampoule wall,with a spacing that increased with ampoule diameter and decreased with freezing rate. The width of the gas tubeswas nearly independent of the ampoule diameter and freezing rate. A high degree of detachment was obtained witha rough, nonwetting coating on the ampoule wall, but full detachment was not achieved. This indicates thatdetachment does not occur by propagation of a single gas bubble around the periphery of the freezing interface. Theconvection near the freezing interface influenced gas bubble formation, and was outward for a concave freezinginterface and inward for a convex interface.